Along with a progress of recent semiconductor devices, semiconductor measurement and inspection techniques are becoming increasingly important. A scanning electron microscope represented by a critical dimension-scanning electron microscope (CD-SEM) is a device for observing a pattern formed on a semiconductor device by performing electron beam scanning over a sample and then detecting a secondary electron emitted from the sample. In order to perform highly precise measurement and inspection on the device like this, it is required to set device conditions properly.
For example, optical axis adjustment of an electron microscope has been disclosed as an optical axis adjustment method using a deflector and a wobbler method in JP 2000-331911 A (PTL 1), JP 2008-084823 A (PTL 2), and JP 2011-054426 A (PTL 3). The deflector deflects an electron beam emitted from an electron source. The wobbler method periodically changes an excitation current of an objective lens.